There has been much discussion over the military's use of chrome plated bolts and carriers in the past. There have been many theories and speculation as to why their use was discontinued. These range from the chrome flaking or wearing off and somehow becoming imbedded into the upper receiver, to the hardness of the chrome carrier itself, both contributing to accelerated wear of the upper receiver. Some claim that these components are brittle and more prone to failure due to the plating process. I believe that most of these commonly held misconceptions revolve around people misinterpreting the intent of the inspection criteria that has been published in the various Technical Manuals printed over the years. The result of these assumptions, combined with failures related to surplus parts that are approaching 40 years of age along with commercially produced parts which are notorious for being substandard, have somehow made all of this theory and speculation internet “fact”. When someone disagrees with this “fact” they are quickly made aware of it’s existence, politely or otherwise by the various experts who can only regurgitate the same information with no supporting documentation.
So, in an effort to not be accused of trolling, I am offering my experience on this subject in how the maintenance system works in an attempt to try and reduce some of the misinformation and the resulting pissing contest relating to this issue. I for one know the documentation quest can be a double edged sword, as there is rarely a smoking gun that can easily answer complicated questions with a simple yes or no. I have spent a fair amount of my time making inquiries and researching the resources I have available to me and still have not found definitive answers to some technical and historical questions relating to the M16 and this topic in particular. In the absence of documentation to support some of these misguided theories we must rely on the available documentation with an understanding of how the military maintenance system works in order to draw an educated conclusion.
The paragraph contained in any era of the TM(Technical Manual) or TB(Technical Bulletin) since about 1972 in any of it’s minor versions including the current TM that covers the A2, A4 and M4 variants that leads to most of this confusion and misinterpretation states:
“There are bolts and bolt carriers on fielded rifles, some with chrome plated exterior surface finishes and some with phosphate coating. Both finishes are acceptable under certain operational requirements and/or restrictions. Phosphate coated bolt carriers are required for divisional combat units. Chrome plated bolt carriers are acceptable for divisional non-combat units and training center units. Chrome plated and phosphate coated bolt assemblies, bolt carrier assemblies, and repair parts for these assemblies may be intermixed in any combination, with the following exception:
Phosphate coated bolt carriers are required for all deployable and deploying units. Chrome plated bolt carriers are acceptable for non-deployable and training center units.”
In the 20 plus years I’ve worked within the system I have never seen one(1) MAM(Maintenance Advisory Message), SOUM(Safety Of Use Message) or even an MWO(Modification Work Order) that addressed the discontinued use of chrome bolt carriers due to a maintenance or safety related issue. Regardless of the era when any of these messages “may” have been published they would still be readily available or their existence confirmed with a little research. As is the same for any system still within the inventory. I have yet to find such a message.
The contention that they would somehow be acceptable for training or CONUS(Continental U.S.) use if they were in fact a safety or maintenance issue is absurd. The U.S. military takes the safety it’s personnel and the operational readiness of it’s equipment very seriously. Any part/component suspected of degrading either, is documented and entirely purged from the system via one of the previously mentioned message types. Even when only a small percentage of the pieces in question are found to be defective. The recent Emco barrel fiasco is a good example of this policy. Once the problem with these barrels surfaced, within a relatively short period of time any weapon having one was identified for a replacement. All this for a non-safety related malfunction found in approximately 5% or less of the rifles with these barrels. If the theory of the plating process reducing the strength or increasing the brittleness of the parts held true, then chrome bolts should suffer a greater rate of failure. This would result in military policy/doctrine completely removing them from the system. Yet, even to this day chrome bolts are acceptable, even in Divisional units. Though rarely encountered these days, I have not seen a chrome bolt that failed headspace or that broke at the cam pin hole or was otherwise unserviceable. Unlike their commercial counterparts. So I think we can put the accelerated wear, malfunctions or safety Theory to rest.
Some will argue that the chrome carrier reflecting light theory was not a valid reason to discontinue use of the chrome carrier as we are trained to always close the ejection port cover. While that may be true by today’s training doctrine, it may not have been the case when the system was first fielded. The same can be said for proper cleaning supplies and training, they evolved with the weapon based on combat usage. This theory does have merit, as I have seen/replaced to many port covers that had become unserviceable due to being bent between the upper and lower receivers by operators during reassembly. The old style port covers were very susceptible to this damage, that’s why we have the new style port covers. This was especially evident on early AR15’s that didn’t have the take down spring reinforcement on the side of the receiver. Early M16’s and XM16E1’s also had this early port cover and suffered the same damage though not as regularly. All three of these models used chromed carriers. So, it was a common occurrence for early rifles with chrome carriers to have an unserviceable port cover resulting in an exposed chrome carrier. Through the evolution of the weapon, when the M16A1 was adopted phosphated carriers had become the spec. Functionally the only part of the carrier that needed chrome plating was the inside. The M16A1 still utilized the old style port cover though.
This leads to the only reasonable conclusion that it is, in fact what the vaguely written and often misinterpreted passages of the inspection criteria in the various TM’s and pre-embarkation standards of the TB’s have always eluded to. It is an “operational” requirement (read that as tactical), NOT to be confused with “operation” as it relates to the functioning of the weapon itself. Basically an attempt to reduce the chance of anything on the weapon that could reflect light or “shine” becoming a liability to a front line troop that alternately would not be considered a liability for training.
The standards set forth in the TM and TB for acceptable over-all finish of the weapon for Divisional combat and rapid deployment units as opposed to Training and CONUS units also supports this reasoning. The amount of SFL(Solid Film Lubricant) authorized for touching up the finish of a weapon is also different for Divisional as opposed to Training/CONUS units further supports this. So it is all boils down to a matter of finish. The more finish on a front line rifle the better. The less shine, the less likelihood of becoming a tactical liability. More importantly though is that front line troops use their weapons more and they are more exposed to the elements. So they are more likely to develop corrosion that could render them unserviceable. Weapons that start life in the field with all or most of their protective finishes usually live longer than those that don’t. But in the instance of the chrome carrier it’s corrosion resistance does not outweigh it’s potential liability.
Wpns Man